Well Bob, you got it right. This is indeed a fake video. There is a
little german man inside the piano making the voices. He comes from a
long lineage of small people who have been cleaning the subway (tube)
here in Montreal. He is closely related to our Montreal Metro-gnomes.
A musical family who are always on time.

I know you write honestly because you have looked inside peoples'
brains and have seen that at the end of the auditory nerve there is
another little person who is sitting on a stool, (shaped a bit like a
toad), listening to the sounds that come up the nerve. And that's how
we really hear.